Concerning the protection of the ozone layer, and phasing out the ozone-depleting substances, the notable Vienna Convention and the Montreal Protocol were signed successively by the main states around the world during 1985-1987. Under this background, the Halon fire extinguishing agents, which were disruptive to the ozone layer, were prohibited in the developed countries in Europe and America, and categorized as substances to be phased out in other countries. In 1992, the China's National Scheme On Phasing Out Ozone Depleting Substances were formulated in China. In the fire protection industry of China, the mission of phasing out Halon 1211 was achieved on Dec. 31, 2005; the production of Halon 1301 was entirely terminated from Jan. 1, 2006; the use of Halon was entirely terminated by the end of 2010. Therefore, in various countries, it has become one of the hot research issues to seek for substitute products for Halon fire extinguishing agents and substitute techniques, which are non-disruptive to the ozone layer of the atmosphere, highly efficient in extinguishing fire, nontoxic and harmless. Currently three categories of substitute products for Halons are widely being developed: haloalkanes, inert gases and aerosol fire extinguishing agents. The aerosol fire extinguishing agent is an extremely highly efficient novel fire extinguishing agent, which has an ozone depletion potential (ODP) of zero. It is nontoxic, harmless, and residual free; it has low price, and the investment demand for its manufacturing equipment is low. Under the urgent background of phasing out Halon, the aerosol fire extinguishing technique is intensively supported by the government, while it also fits the market demand; therefore it becomes one of the remarkable substitute techniques for Halons in the past ten-odd years.
The aerosol fire extinguishing agents, which are mainly divided into two types, S-type and K-type, are composed of oxidants, reductants, burning rate controllers and adhesives. The main fire extinguishing mechanisms of the aerosol fire extinguishing agents are: 1, heat absorption and cooling; 2, chemical inhibition; 3, suffocation; 4, insulation; wherein chemical inhibition is the main mechanism. Though the aerosol fire extinguishing agents are significantly advantageous in aspects like extinguishing efficiency, storage status, construction cost, maintenance, toxicity, secondary damage, environmental friendliness, extinguishing concentration, etc., there are shortcomings in their application, due to the large-scale emission of gas, active particles in the redox reaction, and the simultaneous heat release. In order to effectively decrease the temperature of the device and aerosol, and to prevent the secondary fire, adding a cooling system to the fire extinguishing device is required. Simple physical cooling leads to complicated and bulky structure of the device, complicated process flow and high cost; and due to the presence of the cooling system, large amount of active particles are inactivated, result in greatly degraded extinguishing performance. In addition, affected by the cooling performance, the nozzle temperature of the current aerosol fire extinguishing products is usually too high, which readily harms the operators.